Apparatuses comprising a superabrasive material are utilized for a variety of applications and in a corresponding variety of mechanical systems. For example, polycrystalline diamond elements are used in drilling tools (e.g., inserts, cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire drawing machinery, and in other mechanical systems. More specifically, polycrystalline diamond compacts have found utility as cutting elements in drill bits (e.g., roller cone drill bits and fixed cutter drill bits). Generally, a superabrasive material may be formed by sintering individual superabrasive particles or grains to one another to form a coherent structure, as described in detail below relative to forming polycrystalline diamond.
In one specific example, a polycrystalline diamond compact (“PDC”) typically includes a diamond layer or table formed by a sintering process employing high temperature and high pressure conditions that causes a diamond table or layer to become bonded to a substrate (such as a cemented tungsten carbide substrate), as described in greater detail below. Optionally, the substrate may be brazed or otherwise joined to an attachment member such as a stud or cylindrical backing, if desired. A PDC may be employed as a subterranean cutting element mounted to a drill bit either by press-fitting, brazing, or otherwise locking the cutting element or stud into a receptacle defined by the drill bit. In one example, cutter pockets may be formed in the face of a matrix-type bit comprising tungsten carbide particles that are infiltrated or cast with a binder (e.g., a copper-based binder), as known in the art. Thus, a rotary drill bit may include a plurality of polycrystalline cutting elements affixed to the drill bit body. Such subterranean drill bits are typically used for rock drilling and for other operations which require high abrasion resistance or wear resistance.
A PDC is normally fabricated by placing a cemented carbide substrate into a container or cartridge with a layer of diamond crystals or grains positioned adjacent one surface of a substrate. A number of such cartridges may be typically loaded into an ultra-high pressure press. The substrates and adjacent diamond crystal layers are then sintered under ultra-high temperature and ultra-high pressure conditions (“HPHT sintering”). The ultra-high pressure and ultra-high temperature conditions cause the diamond crystals or grains to bond to one another to form polycrystalline diamond. In addition, as known in the art, a catalyst may be employed for facilitating formation of polycrystalline diamond. In one example, a so-called “solvent catalyst” may be employed for facilitating the formation of polycrystalline diamond. For example, cobalt, nickel, and iron are among examples of solvent catalysts for forming polycrystalline diamond. In one configuration, during HPHT sintering, solvent catalyst within the substrate body (e.g., cobalt from a cobalt-cemented tungsten carbide substrate) becomes liquid and sweeps from the region adjacent to the diamond powder and into the diamond grains. Of course, a solvent catalyst may be mixed with the diamond powder prior to sintering, if desired. Also, as known in the art, such a solvent catalyst may dissolve carbon. Thus, carbon may be dissolved from the diamond grains or portions of the diamond grains that graphitize due to the high temperatures of HPHT sintering. The solubility of the stable diamond phase in the solvent catalyst is lower than that of the metastable graphite under HPHT sintering conditions. As a result of this solubility difference, the undersaturated graphite tends to dissolve into solution and the supersaturated diamond tends to deposit onto existing nuclei to form diamond-to-diamond bonds. Thus, diamond grains become mutually bonded to form a polycrystalline diamond table upon the substrate. Subsequent to HPHT sintering, the solvent catalyst may remain in the polycrystalline diamond layer within the interstitial pores between the diamond grains or the solvent catalyst may be at least partially removed from the polycrystalline diamond, as known in the art. For instance, the solvent catalyst may be at least partially removed from the polycrystalline diamond by acid leaching. A conventional process for forming polycrystalline diamond cutters is disclosed in U.S. Pat. No. 3,745,623 to Wentorf, Jr. et al., the disclosure of which is incorporated herein, in its entirety, by this reference. Optionally, another material may replace the solvent catalyst that has been at least partially removed from the polycrystalline diamond.
One of ordinary skill in the art may appreciate that providing superabrasive (e.g., polycrystalline diamond), superabrasive (e.g., polycrystalline diamond) compacts, apparatuses, structures, or other articles of manufacture including material with improved properties and methods of manufacture may be advantageous.